- Fix bitcoin-overview image (P2PKH address was used as "private key")
- Use receiving and sending images from Bitcoin Design Guide
(https://bitcoin.design) under CC-BY license
(https://github.com/BitcoinDesign/Guide/blob/master/LICENSE)
- Mention changeless outputs, especially as used in transaction-chain
image
- Include brief mention of best blockchain in paragraph about the cost
to miners for confirming conflicting transactions